Translator: Michele Gianella Reviewer: Denise RQ
Thank you.
Good morning everybody!
(Applause)
We have just listened in music
what we want to do in computer science:
the transition from the traditional to the quantum computer,
from bit to qubit in tomorrow's technology.
Such technology should exploit quantum mechanics,
behaviors that although bizarre
- and behind me, in this image,
we have a really strange behavior -
if instead of the two skiers behind me,
there were some electrons,
these behaviors actually do happen.
So it's like, from the weird world of quantum mechanics
to tomorrow's quantum computer.
In order to appreciate the innovation a quantum computer would represent,
let's start from our current ones,
from the current technological limits yet to be overcome.
Even today's computer saw the light
thanks to a breakthrough, the invention of the transistor,
made by the three researchers
we see in the photo behind me,
Shockley, Bardeen, and Brattain,
all Nobel Prize recipients, 60 years ago now,
for the invention of the transistor,
another brainchild of quantum mechanics,
based as it is on the discovery of the atomic structure.
The transistor --
a fundamental unit of all our modern technology.
All microprocessors contain a huge number of transistors.
Think about this: should all of us, in this room,
put all our technology together,
we have more than a trillion transistors,
all packed together on these microprocessors:
a staggering figure.
How far can we get to?
How far can we increase the computing power?
Clearly it all depends on how long we can keep shrinking transistors.
Here we have instead the curve,
the so-called Moore's law
according to which transistors' number doubles approximately every 18 months.
Will there be a moment however
when this surge in the number of transistors hits a limit?
Certainly yes: a wall will be hit
when we get to the limit of the atomic scale.
We can't imagine to make a transistor smaller than an atom.
So what will we do then?
Shall we settle down with our technology?
No.
Instead, we'll take advantage of quantum mechanics' quirks,
not as a limit but as a huge opportunity,
as a resource that will allow us to go further.
Quantum mechanics,
this institution of modern physics
- here's one of the most famous meetings,
you'll certainly recognize some of them in this photo -
which describes the behavior
of particles, atoms, but also molecules,
So it depicts the structure of the atom
through the breakthrough of the wave function,
which describes the behavior of atomic systems
- thus on a very small scale.
Which quantum mechanics behaviors
would we like to use in tomorrow's computers?
The first and foremost
is the so-called quantum superposition:
the wave function can be
- and actually is, for microscopic systems -
the sum of all behaviors.
Atomic systems are in several states at once,
in all states allowed by quantum mechanics.
So if an electron can either go right or left,
in quantum mechanics,
it will go both right and left at the same time.
The second quirk in quantum mechanics
is the well known "Entanglement,"
namely an intertwining
between the particles that either were born together or have interacted.
If for example we take two particles, called Alice and Bob,
who are in an entangled state,
even if we place them far apart,
if something happens to Bob, Alice will be instantly affected.
To use a rather romantic metaphor,
it is like for two lovers,
they are also, somewhat, in an entangled state.
These properties made Niels Bohr,
one the founding fathers of quantum mechanics,
say about this theory - and how couldn't we agree.
Those who aren't shocked by quantum mechanics
cannot possibly have understood it.
So, starting from these two milestones,
superposition and entanglement,
Richard Feynman and David Deutsch, portrayed in these pictures,
have proposed the creation of a new type of computer
which is conceptually very different than current ones.
How different would this computer be?
Current computers work
by processing the so-called bits,
a stream of 0 and 1 which ultimately
return final results via algorithms.
In quantum mechanics instead,
by using the superposition of states,
we can use 0 and 1 simultaneously.
This would clearly trigger
an exponential increase in the computational power.
And consequently, much faster and much more powerful computers.
Bit 0 --
(Piano music)
Let me show you how the switch would feel like.
Bit 1 --
(Piano music)
The Qubit, instead --
(Piano music)
Really amazing.
Ladies, wouldn't it be...
(Applause)
It'd be so cool if we ladies could sometimes
be in an entangled state and do more things at once.
But we are too big: billions of atoms together
who don't keep the state of quantum superposition.
So, if it's a bowl of cherry, where is this quantum computer?
Why don't we have it yet?
Because it is very hard to generate superposition states,
and it's even harder to preserve it,
And that's what we are trying to do.
Let's look at the enemy.
The goal is a quantum symphony --
(Piano music)
But if something interrupts the pianist,
for example, he checks his phone.
What happens?
It loses coherence,
the qubit disappears, the system doesn't work any longer.
So decoherence is our enemy,
and it often shows up.
It destroys the Qubit,
so the entangled state, the entangled behavior,
the quantum superposition state we wanted to work on is no more.
It's vanished, gone away.
Studies are made in many labs around the world
to keep the qubit,
create it and keep it alive.
Even the group
I have the pleasure and duty to coordinate in an experiment
in the laboratories of Gran Sasso, under the mountain,
in this wonderful lab connecting l'Aquila and Teramo,
we are trying, on atomic and nuclear systems,
to work on quantum superposition and to find limits
or conditions that will allow future quantum technologies
to be more accessible than they are now.
Some prototypes of quantum computer are already in place,
you can see them in these images.
Sure, they're very complex, the size of a wardrobe.
But let's not forget that even our computers
were that bulky, many years ago.
This gives us hope that tomorrow's quantum technologies
will allow us to make this incredible computer.
What will it do then?
20 years from now, we think this computer
will give us quantum cryptography and a real cyber security.
Information thieves, hackers, will have a much harder time:
the moment they sniff the traffic, they're detected,
because they destroy the quantum coherence.
They will be useful to study chemistry,
molecular systems in biology and in medicine;
and even to study the human brain,
this extraordinary structure
made of billions and billions of neurons.
Last but not least, in a globalized world they'll do a much better job
at handling big data:
we live with big data and quantum computers
will help us solve and analyze more quickly these big data.
So, to wrap up, I just point out that quantum technologies
and the passage through a quantum symphony
from the bit generation
(Piano music)
to the Qubit generation
(Piano music)
will change our world.
It's amazing, it's challenging, but it's also fun.
So let's do it.
Thanks to...
(Applause)
Many thanks to Venceslao Marinaro.
Thanks.
(Applause)